Correlation between Quantitative Morphometric Pulmonary Vascular Structures and Postoperative Transpulmonary Pressure Gradient following Fontan Procedure

Abstract

The prognosis of Fontan operation mainly depends on the pulmonary vascular resistance, but it is difficult to know it preoperatively. According as the pulmonary vascular resistance is proportional to the transpulmonary pressure gradient, we measured transpulmonary pressure gradient and percentage medial thickness with lung biopsy tissues, and examined the correlation between them. Thirty four patients who had undergone Fontan operation from Feb. 1989 to Dec. 1991 were subject to lung biopsy in order to measure Heath-Edward grade and the pulmonary arterial percentage medial thickness by quantitative morphometric analysis. And we examined the correlation between the postoperative transpulmonary pressure gradient and the pulmonary arterial percentage medial thickness. The difference of percentage medial thickness depending on age or shunt operation was also examined. Data showed no difference between Heath-Edward grade 0 and other grades in the transpulmonary pressure gradient. The patients undergone shunt operation did not show any difference in the percentage medial thickness compared to ones who did not. However, the study showed significant correlation between postoperative second day transpulmonary pressure gradient and percentage medial thickness in pulmonary arterial diameter of 20-50,LIM with the correlation coefficient of 0.445 (p=0.03). We conclude that pulmonary vascular resistance is generated mainly by diameter 20-50IlM pulmonary arteries, and it partly depends on their percentage medial thickness. This result suggests that assessment of the percentage medial thickness of 20-5011M pulmonary arteries on lung biopsy is helpful in prediction of postoperative transpulmonary pressure gradient and prognosis following Fontan operation.